The present invention relates to bulldozers or the like having transversely extending blades, and more particularly to a blade stabilizing linkage and controls therefore mounted between the vehicle and bulldozer blade for resisting side loading and lateral stresses applied to the blade.
The blade of many earth-working vehicles is typically pivotally mounted forwardly of the front end of the main frame or push arms which extend rearwardly and flank the track frames. The push arms are pivotally connected to the track frames near the rear of the vehicle. The problem of resisting side loading upon bulldozer blades is well-known in the prior art and a number of stabilizing linkages have been proposed as solutions.
It is conventional practice to provide diagonal braces extending between the push arms and the back of the blade for resisting such side loads. These diagonal braces typically prevent the blade from being mounted close to the tractor by requiring substantial spacings between the blade and the vehicle which is undesirable. These prior art devices have required that the blade be positioned sufficiently forward to provide the necessary clearance with the forward ends of the tracks for the blade to be raised and lowered. There has been a need for a stabilizing linkage capable of resisting side loads while permitting the blade to be mounted close to the forward end of the tractor thereby improving machine stability and manueverability.
There are many instances where off-center loading of the blade occurs such as when the tractor is operating against a side hill. Large forces that can cause lateral shifting of the blade also occur when the vehicle is changing direction and the blade is engaged with the earth. The push arms and blade form a U-shaped structure which is not adjustable to withstand side loads. The spacing between the push arms and adjacent track frames must be maintained or possible contact between the push arms and track can result. There has been a need for a stabilizer link which prevents appreciable sidewise motion of the blade to the point that contact between the push arms and track occurs with resulting damage or injury.
The prior art stabilizing linkages have prevented other desirably features in connection with blade mounting and movement on the tractor. Many such linkages cannot be adapted to permit vertical, tilting, and angling movement of the blade relative to the vehicle frame without undesirably increasing the clearance between the track frames, push arms, and blade which adversely affects the overall length of the machine and its balance.
Another problem associated with prior art stabilizing linkages is that they are not adequately adjustable or controlled to compensate for the various degrees of off-center loading in the blade. The stabilizing link should also be capable of resisting lateral forces imposed on the blade at any vertical position of the blade. To resist the lateral loads imposed by off-center operation of the tractor, the prior art braces have been extremely bulky, relatively complex, and expensive to provide maximum resistance to the side loads. It is not unusual that larger than expected loads are encountered which cause the braces to fail, thereby requiring larger and more expensive replacement configurations. There has been a need for an adjustable stabilizer link that is controlled to respond when various degrees of lateral load are imposed on the bulldozing blade and when the blade assumes various vertical positions.
These disadvantages of present bulldozer stabilizer linkages have resulted in the stabilizing linkage and controls therefore in the present invention which is capable of resisting side loads upon the blade and also permitting close coupling of the blade relative to the machine upon which it is supported.